curvature versus slope
  n = 458023 
  X=0, Y = 8.60 +/- 3.68 
  Weighted least-squares fit:  Y = 8.4 + 0.673 X  + -0.01230 X**2 

slope versus dZ, curvature < 5
  n = 256891 
  X=0, Y = 12.09 +/- 8.41 
  Weighted least-squares fit:  Y = 11.9 + -0.184 X  + 0.01204 X**2 
     at X = 100, Y = 113.9 
     effective RMSE xy = 177.9 

slope versus dZ, curvature < 15
  n = 417921 
  X=0, Y = 12.32 +/- 8.54 
  Weighted least-squares fit:  Y = 12.5 + -0.097 X  + 0.00938 X**2 

curvature versus dZ, slope < 10
  n = 333589 
  X=0, Y = 10.46 +/- 6.70 
  Weighted least-squares fit:  Y = 10.3 + 1.447 X  + 0.05976 X**2 


Number of samples 458024
Max dz = 95
Mean dz = 10
RMS dz = 13.2664991614
100cm = 0 percentile value of dz